JP4212569B2 - Switching device - Google Patents

Description

  The present invention relates to a switching device that performs switching control that repeats an ON operation and an OFF operation of a power switching element.

  As this type of switching device, for example, there is a switching device used in an in-vehicle power electronics device. In a vehicle equipped with such a switching device, noise due to the operation of the switching device may be superimposed on the frequency of a broadcasting station selected by an in-vehicle radio receiver or the like. When noise is superimposed on the frequency of the selected broadcasting station, the noise is mixed into the frequency (sound) of the audible range output from the car audio speaker, causing discomfort to the user.

  In order to reduce such noise, a technique for reducing the energy level of an average noise by dispersing energy of harmonic components of the switching frequency by spread spectrum or the like is well known. However, although such technology can reduce the energy of noise due to each switching frequency and their respective harmonics, when the switching frequency and its harmonics overlap with the frequency of the selected broadcast station. It is inevitable that noise is output from the speaker.

  In order to reduce the noise output from the speaker, a noise filter may be provided on the output side of the switching device. However, in order to sufficiently remove the noise from the speaker, the filter is complicated and enlarged. Is inevitable.

  Therefore, conventionally, for example, as seen in Patent Documents 1 and 2 below, the switching frequency may be set so that the harmonics of the switching frequency have a predetermined relationship with the frequency band of the selected broadcasting station. Proposed. That is, for example, by setting the switching frequency so as to have a specified frequency difference from the frequency of the selected broadcast station, it is possible to avoid the output of noise from the speaker.

However, since the switching frequency can change due to variations in the component elements of the switching device, it is difficult to set the switching frequency while maintaining a predetermined relationship with the frequency band of the selected broadcast station. Yes. Moreover, for example, the frequency band (bandwidth) of one AM radio station is “9 kHz” in Japan and “10 kHz” in the United States, and a switching frequency that maintains a predetermined relationship with such a narrow frequency band is set. That is not realistic.
JP 2002-335672 A JP 2003-88101 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a switching device that performs switching control in a manner that can suitably suppress disturbance of transmission of auditory information due to noise associated with switching control. Is to provide.

  Hereinafter, means for solving the above-described problems and the effects thereof will be described.

  Means 1 includes a switching device that performs switching control that repeats an on operation and an off operation of a power switching element, and includes a timing at which one of the on operation and the off operation is different from each other with respect to a basic period. This is performed while shifting by a plurality of shift amounts, and at least one of the switching frequency created by the interval between the start timings and the harmonics thereof is intermittently connected to a predetermined frequency desired for noise suppression for the switching device. When the overlap occurs, the reciprocal of the period from the overlap to the next overlap is set not to fall within the audible frequency band.

  In the above configuration, the start timing of at least one of the on operation and the off operation is performed while being shifted by a plurality of shift amounts including different ones with respect to the basic cycle. For this reason, since the switching frequencies created by the interval between the at least one start timings include those that do not overlap, the switching frequencies are spread compared to when the switching frequencies are all equal, and as a result, noise caused by switching control is spread. The average level can be reduced.

  However, even if the average level of noise is reduced, a signal (audio signal) having auditory information of a predetermined frequency when the spread switching frequencies and their harmonics overlap with the predetermined frequency. There is a risk of noise mixing. In this regard, in the above configuration, the reciprocal of the period between the timings at which the overlap occurs is set so as not to enter the audible frequency band. As a result, even if the predetermined switching frequency and the spread switching frequency and its harmonics overlap, the noise finally output from the speaker due to these spreading switching frequencies and their harmonics is the audible frequency. Since it does not enter the band, it is possible to suitably suppress disturbance of transmission of auditory information due to the noise.

  The means 2 shifts the start timing of any one of the on operation and the off operation by repeating a basic pattern including a plurality of shift amounts including different ones with respect to a basic period. Phase shift means is provided, and the spread frequency that is the reciprocal of the repetition cycle of the basic pattern is set to be higher than the audible frequency.

  In the above configuration, the start timing of at least one of the on operation and the off operation is shifted according to the basic pattern including a plurality of shift amounts including different ones with respect to the basic cycle. For this reason, since the switching frequency created by the interval between the at least one start timing includes different ones, the switching frequency is spread compared to when they are equal, and consequently the average level of noise caused by the switching control is increased. Can be reduced.

  Further, in the above configuration, when the spreading frequency that is the reciprocal of the repetition cycle of the basic pattern is set to be higher than the audible frequency, the switching frequency created by each of the intervals between the at least one start timings overlaps the predetermined frequency. Thus, it is possible to reliably eliminate the reciprocal of the period from one overlap to the next overlap within the audible frequency band.

  The means 3 is characterized in that, in the means 2, the basic pattern is set such that the shift amounts of any one of the start timings are different from each other.

  In the above configuration, the switching frequency formed by the interval between the start timings of at least one of the on operation and the off operation can be more suitably spread.

  The means 4 in the means 2 or 3, wherein the phase shift means stores a plurality of basic shift amounts including different ones, information on the order of the plurality of basic shift amounts, and an offset value. And the basic pattern is generated by appropriately arranging the basic shift amount and the basic shift amount obtained by adding the offset value alternately. To do.

  In the above configuration, the basic pattern has a basic shift amount and a value obtained by adding an offset value to the basic shift amount as appropriate. For this reason, in addition to the information about the basic shift amounts and their order, the number of shift amounts of the basic pattern can be increased with respect to the basic shift amount only by storing the offset value.

  The means 5 is the means 3 in which the phase shift means is configured such that harmonics of each switching frequency generated by each of the intervals between the start timings of the respective ones in the frequency band in which noise countermeasures for the switching device are desired. The shift amount is set so as not to overlap.

  In the above configuration, harmonics of the switching frequency are set so as not to overlap in a frequency band where noise countermeasures are desired. For this reason, even if the predetermined frequency overlaps with a specific harmonic, since the specific harmonic is one, the noise level superimposed on the predetermined frequency is reduced. Furthermore, by setting such a setting, it is possible to avoid the predetermined frequency and the harmonics generated by each of the switching frequencies from overlapping each other. Even if it overlaps, it can be surely made intermittent.

  The frequency band may be equal to the predetermined frequency or may be a frequency band including this frequency band.

  The means 6 may be any one of the means 1 to 5, wherein the phase shift means determines a start timing for the basic period for the other of the on operation and the off operation between the start timings of the on operation. Duty variably controlled according to the duty required when controlling the control target to a desired control amount under the condition that the switching frequency created by each of the interval and the start timing of the off operation does not overlap each other Control means is provided.

  In the above configuration, if the start timing with respect to the basic period for one of the other is variably set according to the required duty, the interval between the other start timings (starting with the basic pattern may be used depending on the duty setting mode). The switching frequencies created by those whose timing is not defined) may overlap each other, and the switching frequencies and the switching frequencies defined by the basic pattern may overlap each other. When these overlap, the noise energy level increases at the overlapping frequency and an integer multiple of the overlapping frequency. In this regard, in the above configuration, since the other start timing is variably controlled on the condition that the switching frequency formed by the interval between the start timings of the on operation and the interval between the start timings of the off operation does not overlap each other, the start timing It is possible to avoid an increase in noise energy level due to the overlap between the intervals.

  In the means 7, the duty control means controls the average duty represented by the ratio of the total time of the on period or the total time of the off period to a predetermined period to a control amount that makes the control object desired. The variable control is performed under the condition of the duty required at the time.

  When the duty in each basic cycle is variably controlled, the switching frequencies formed by the interval between the start timings of the on operation and the off operation may overlap each other depending on the required duty. In this regard, in the configuration described above, it is possible to avoid the switching frequencies from overlapping with each other, for example, by making some of the basic cycles different from each other. Moreover, by setting the average duty to the required duty, it is possible to set the required duty while preferably avoiding the switching frequencies from overlapping each other.

  The means 8 is the means 6 or 7, wherein the duty control means is configured to determine an interval between the start timings of the on operation and an interval between the start timings of the off operation in a frequency band in which noise countermeasures for the switching device are desired. The duty variable control is performed with a duty that does not overlap a plurality of harmonics of the switching frequency to be generated.

  In the above configuration, by performing variable duty control at a duty at which a plurality of harmonics of the switching frequency do not overlap, an increase in noise level at the same harmonic frequency due to the overlap of harmonics can be avoided.

  The frequency band may be equal to the predetermined frequency or may be a frequency band including this frequency band.

  Means 9 is that in any one of means 1 to 8, the predetermined frequency is a frequency within a frequency band of radio broadcast, and overlapping with the predetermined frequency means that a frequency difference from the predetermined frequency is the wireless frequency. It is characterized by being within the bandwidth per broadcasting station of broadcasting.

  Each broadcasting station for wireless broadcasting has a predetermined frequency width (bandwidth). In this regard, in the above configuration, by defining the overlap using the bandwidth per broadcasting station, it is possible to make a setting that appropriately copes with the overlap between the frequency of each broadcasting station and the switching frequency and its harmonics. .

  Means 10 is that, in means 5 or 8, the desired frequency band of the noise band is a frequency band of radio broadcast, and the harmonics overlap, the frequency difference between them per broadcast station of the radio broadcast It is characterized by being within the bandwidth.

  Each broadcasting station for wireless broadcasting has a predetermined frequency width (bandwidth). In this regard, in the above configuration, by defining the overlap using the bandwidth per broadcasting station, it is possible to appropriately eliminate the overlapping of a plurality of harmonics within the frequency of each broadcasting station.

  In any one of the means 2 to 10, the means 11 is a ringing caused by a surge caused by at least one of the on operation and the off operation, wherein a difference of another shift amount with respect to an arbitrary shift amount among the plurality of shift amounts. When the period is Tr, it is characterized by being set to “Tr × 1/4” or more.

  In switching control, surge noise may occur with the on / off operation. When auditory information is transmitted using a frequency band substantially equal to the frequency of ringing due to the surge, the transmission of auditory information may be disturbed by the surge or ringing. In particular, the surge energy level is higher than the ringing energy level, and the transmission of auditory information due to this is likely to be noticeable.

  In this regard, in the above configuration, by setting the difference of each other shift amount with respect to an arbitrary shift amount to “Tr × 1/4” or more, it is possible to avoid the occurrence of a surge at the same cycle every time. As a result, noise energy due to surge can be suitably diffused.

(First embodiment)
Hereinafter, a first embodiment in which a switching device according to the present invention is applied to a switching device of a DC-DC converter mounted on a hybrid vehicle will be described with reference to the drawings.

  FIG. 1 shows the configuration of the hybrid vehicle. In this hybrid vehicle, the driving forces of the internal combustion engine 2 and the motor generator 4 are transmitted to the shaft 8 and the driving wheels 10 via the power distribution device 6.

  The motor generator 4 has a function of generating power by the driving force applied from the power distribution device 6 in accordance with the driving state of the vehicle, in addition to the function of applying the driving force to the power distribution device 6. . The motor generator 4 is connected to a power control unit 14 including a DC-DC converter, an inverter, and a high voltage battery. The power control unit 14 converts AC power generated by the motor generator 4 into DC power and stores it as high-voltage power. Further, the power control unit 14 steps down the high voltage power and supplies it to the battery 16.

  Further, the hybrid vehicle is equipped with a radio receiver 18 and a speaker 19. The radio receiver 18 includes an AM receiver and an FM receiver. Here, the AM receiver detects and demodulates the modulated wave whose carrier wave is modulated by analog AM modulation, and outputs it to the speaker 19 as an audio signal. The frequency band of this AM broadcast is, for example, “510 to 1720 kHz”. On the other hand, the FM receiver detects and demodulates the frequency-modulated modulated wave and outputs it to the speaker 19 as an audio signal. The frequency band of this FM broadcast is, for example, “76 to 108 MHz”.

  FIG. 2 shows the configuration of the DC-DC converter and its control device (switching device) in the power control unit 14.

  The DC-DC converter 20 is configured as an insulating DC-DC converter 20. That is, the series circuit of the high voltage battery 15 that stores the AC power of the motor generator 4 shown in FIG. 1 converted into DC power by the inverter, the power switching element 26 and the coil 23a of the transformer 23, and the battery 16 And a low voltage circuit that outputs low voltage power. Here, in the low voltage circuit, a diode 27 and a coil 28 are connected in series to the coil 23 b of the transformer 23. A diode 22 is connected between the diode 27 and the coil 28 and the ground, and a capacitor 24 is connected between the output side of the coil 28 and the ground. In such a configuration, the output of the DC-DC converter 20 is controlled by switching control that repeatedly turns on and off the power switching element 26.

  The switching control is performed by the microcomputer 30. The microcomputer 30 includes a central processing unit, a memory 32, and the like. Then, the output of the DC-DC converter 20 is taken in, and the power switching element 26 is turned on and off via the driver 40 in order to control the output of the DC-DC converter 20 to a desired output (switching control is performed). ). More specifically, the power switching element 26 is turned on and off by outputting a drive pulse to the power switching element 26 via the driver 40.

  However, depending on the mode of the switching control, noise may be superimposed on the frequency of the broadcasting station selected by the receiver 18 due to the switching control. The noise caused by the switching control includes not only radiation noise caused by the switching control but also noise transmitted through the lines L1 and L2 shown in FIG. That is, the line L1 on the ground side of the receiver 18 is connected to the power control unit 14 (specifically, the DC-DC converter 20), and the line L2 connecting the receiver 18 and the battery 16 is the power control unit. 14 (specifically, the DC-DC converter 20), the noise from the DC-DC converter 20 enters the receiver 18 via the lines L1 and L2.

  The mixing of noise into the receiver 18 due to the switching control occurs when the frequency for switching control and its harmonics overlap with the frequency of the broadcast station received by the receiver 18. Hereinafter, this will be described with reference to FIGS.

  FIG. 3A shows the drive pulse for driving the power switching element 26. Incidentally, the power switching element 26 is turned on over the rising period (period of logic “H” level) or the falling period (period of logic “L” level) of the drive pulse. For example, when power switching element 26 is an N-channel MOS transistor, power switching element 26 is turned on while the drive pulse is at a logic “H” level. For example, when the power switching element 26 is a P-channel MOS transistor, the power switching element 26 is turned on while the drive pulse is at the logic “L” level. In the following description of the present embodiment, a case where the power switching element 26 is turned on during the logic “H” level of the drive pulse will be described as an example.

  In FIG. 3A, the interval Th between the rising edges of the drive pulses (on operation start timing) and the interval Tl between the falling edges of the drive pulses (off operation start timing) are set to be equal to each other. For this reason, as shown in FIG. 3B, the switching frequencies fh and fl, which are the reciprocal numbers thereof, are equal to each other, so that the noise energy level increases at the switching frequencies fh and fl (in FIG. 3B). For the sake of convenience, the switching frequencies fh and fl are slightly shifted. Therefore, as shown in FIG. 3C, the switching frequency fh (fl) and its harmonics “fh × 2, fh × 3, fh × 4, fh × 5 (fl × 2, fl × 3, fl × The energy level of noise increases at a frequency of “4, fl × 5)”.

  FIG. 4 shows experimental values of noise energy levels when switching control is performed using the drive pulses shown in FIG. As shown in the figure, both the peak noise indicated by the solid line and the average noise indicated by the broken line have large energy levels.

  Here, in order to reduce the energy level of noise caused by the switching frequency, the following control can be considered. (A) In PWM control, the period during which each drive pulse rises is randomized. (B) PWM control is performed by setting a plurality of frequencies. (C) Switching control is performed by a pattern that is diffused so that the timing of the rising edge and falling edge of the drive pulse does not become a constant period.

  FIG. 5 shows a typical noise energy level when switching control is performed by such a method. As shown in the figure, the average noise energy level is greatly reduced by performing the switching control by the above method (in the experiment shown in FIG. 5, the average is compared with the one shown in FIG. 4). The energy level of noise has been reduced).

  However, although the energy level of noise is reduced, back noise is output via the speaker 19 when the switching frequency and its harmonics overlap with the frequency of the broadcast station received by the receiver 18. Of course, if the switching frequency and its harmonics are set so as not to overlap with the frequency of the broadcasting station, the back noise can be eliminated. However, as described above, this setting is difficult.

  Therefore, in this embodiment, the start timing of the ON operation (rising edge of the drive pulse) is shifted by repeating a basic pattern composed of a plurality of different shift amounts with respect to the basic cycle, and the basic pattern is repeated. The spreading frequency that is the reciprocal of the period is set to be higher than the audible frequency.

  FIG. 6A shows an example in which the rising edge of the drive pulse is shifted by repeating a basic pattern consisting of three different shift amounts with respect to the basic period. Here, the rising edge (phase thereof) is sequentially shifted by the shift amount φ0 to φ2 with respect to the basic period T1. Here, the amount by which the rising edge of the drive pulse is shifted with respect to the basic period T1 is a repetition of three shift amounts φ0 to φ2, as shown in FIG. 6B. For this reason, the interval T01 between the rising edges of the drive pulse shifted by the shift amount φ0 and the shift amount φ1, the interval T12 between the rising edges of the drive pulse shifted by the shift amount φ1 and the shift amount φ2, and the shift The switching frequencies F01, F12, and F20 created by the interval T20 between the rising edges of the drive pulse shifted by the amount φ2 and the shift amount φ0 can be made different from each other. For this reason, it is possible to spread the frequency as compared with the case where the switching frequency formed by the interval between the rising edges of each drive pulse is equal. As shown in FIG. 6C, the noise energy level (case K2) when the switching frequency is diffused is compared with the noise energy level (case K1) when the switching frequencies match. Thus, the average level of noise can be reduced.

  However, even if it is set in this way, noise is output from the speaker 19 if any of the switching frequencies or harmonics thereof overlaps the frequency of the AM broadcast station received by the receiver 18. Is done. Here, in this embodiment, the spreading frequency that is the reciprocal of the period T of the basic pattern is set to be equal to or higher than the audible frequency. Thus, even if any of the switching frequencies, or any of their harmonics, intermittently overlaps with the frequency of the AM broadcast station received by the receiver 18, The reciprocal of the period is greater than or equal to the audible frequency. For this reason, since the noise finally output from the speaker 19 does not enter the audible frequency band, the superimposition of the audible noise on the audio signal of the broadcasting station output from the speaker 19 can be suitably suppressed.

  Incidentally, the audible frequency or higher may be, for example, “20 kHz” or higher. This is because the audible frequency is said to be “20 Hz to 20 kHz”. However, this setting is not absolute. Actually, there are individual differences in human hearing ability, and for example, human beings who can catch a sound wave of “20 kHz” are rare. For this reason, even if the spreading frequency is set to, for example, “15 kHz” or more, a remarkable effect can be obtained.

  Here, the spreading | diffusion aspect of the said switching frequency is explained in full detail.

  When spreading the switching frequency according to the basic pattern, when the switching frequency is the AM radio broadcast band, the frequency difference between the spread switching frequencies is equal to or greater than the frequency width (bandwidth) per station of the AM radio broadcast station. Have something to become. That is, for example, since the bandwidth per station of Japanese AM radio broadcasting is “9 kHz”, normally, the bandwidth allocated to each station is determined in advance. The frequency is spread in such a way that there are those having the above differences.

  When the lower harmonics of the switching frequency are in the AM broadcast band, when spreading the switching frequency, the frequency difference between the harmonics in the AM broadcast band is one of the AM radio broadcast stations. Make sure it has more than the per-bandwidth.

  Thereby, even if the frequency of the broadcasting station received by the receiver 18 and the switching frequency or their harmonics match, it is avoided that the switching frequency or all of those harmonics match the specific broadcasting station. can do. For this reason, even if it is a case where the frequency of a broadcasting station, a switching frequency, or those harmonics overlap, the overlap can be made intermittent.

  In this way, the overlap between the switching frequency and their harmonics and the frequency of the broadcasting station is made intermittent, and the reciprocal of the period from one overlap to the next is made higher than the audible frequency by setting the basic pattern. By doing so, the noise output from the speaker 19 can be driven beyond the audible range.

  However, when the switching frequency and their harmonics overlap with the frequency of the broadcasting station, even if the reciprocal of the period between the overlapping timings is higher than the audible range, There arises a disadvantage that the energy level of radiation noise rises during switching control. Further, even if the switching frequencies F01 to F20 formed by the intervals T01 to T20 between the rising edges of the drive pulse are diffused in the mode shown in FIG. 6, these harmonics overlap as shown in FIG. there is a possibility. Incidentally, in FIG. 7, the Nth-order harmonic of the switching frequency F20 and the (N + 1) th-order harmonic of the switching frequency F01 overlap each other.

  Hereinafter, a method for reducing the switching frequency generated by the rising edge of the drive pulse and the energy level of the harmonics thereof will be described in detail.

  In order to reduce the average energy level of the switching frequency created by the interval between the rising edges of the drive pulses and the radiation noise of their harmonics, the switching frequency and their harmonics are in a frequency band where noise countermeasures are desired. It is best to avoid overlapping as much as possible. On the other hand, in the present embodiment, it is assumed that the repetition period T of the basic pattern shown in FIG. 6 and the shift amounts φ0 to φ2 are set so that the switching frequency is in the range of “20 kHz to 1000 kHz”. ing. Therefore, since the switching frequency or a relatively low-order harmonic overlaps with the AM broadcast band, in this embodiment, noise countermeasures in the AM broadcast band are particularly desired.

In FIG. 6, the switching frequencies F01, F12, and F20 created by the intervals T01, T12, and T20 are as follows.

F01 = 1 / {T1-φ0 + φ1}
F12 = 1 / {T1-φ1 + φ2}
F20 = 1 / {T1-φ2 + φ0}

Here, the condition that these switching frequencies do not overlap with each other in the AM broadcast band should satisfy the following condition when they are in the AM broadcast band.

| F01−F12 | ≧ bandwidth (c1)
| F12-F20 | ≧ bandwidth (c2)
| F20-F01 | ≧ bandwidth (c3)
On the other hand, the conditions for preventing the harmonics of the switching frequency from overlapping each other in the AM broadcast band are as follows. First, let L, M, and N be the orders of harmonics in the AM broadcast band among the respective harmonics of the switching frequencies F01, F12, and F20. Here, L, M, and N are integers of 2 or more, and these values are not limited to one. At this time, the following conditions may be satisfied.

| L × F01−M × F12 | ≧ bandwidth (c4)
| M × F12−N × F20 | ≧ bandwidth (c5)
| N × F20−L × F01 | ≧ bandwidth (c6)
Incidentally, the conditions for the switching frequency can be included in the conditions (c4) to (c6) by making the L, M, and N natural numbers. However, L, M, and N are set to values within the AM broadcast band by multiplying F01 to F20. Further, when the basic pattern is φ0, φ1, φ2,... Φn, the above condition can be generalized as follows.

  First, the switching frequency generated by the basic pattern is Fij (i = 0 to n, j = i + 1; provided that j = 0 if j = n + 1). Of these switching frequencies or their harmonics, the one that overlaps the AM broadcast band is defined as Pij × Fij. However, Pij is a natural number, and is a number for multiplying Fij to make the multiplication value the AM broadcast band.

  At this time, the following conditions may be satisfied.

| Pij × Fij−Pi′j ′ × Fi′j ′ | ≧ bandwidth (c7)
However, “i” and “i ′” are different from each other, and “j” and “j ′” are also different from each other.

  For example, in the basic pattern shown in FIG. 6, if “φ0 = 0 μsec”, “φ1 = 0.3 μsec”, “φ2 = 0.31 μsec”, “T1 = 10 μsec”, “T = 30 μsec”, “F01 = 96.933 kHz "," F12 = 100.1 kHz ", and" F02 = 103.093 kHz ". These switching frequencies and their harmonics are as shown in FIG.

  As illustrated, in this case, frequency overlap does not occur in the AM broadcast band. Moreover, the spreading frequency which is the reciprocal of the repetition period T of the basic pattern is “33.3 kHz”, which is set to be higher than the audible frequency.

  On the other hand, in the basic pattern shown in FIG. 6, if “φ0 = 1 μsec”, “φ1 = 2 μsec”, “φ2 = 3 μsec”, “T1 = 10 μsec”, “T = 30 μsec”, “F01 = 83 .333 kHz ”,“ F12 = 90.909 kHz ”, and“ F02 = 142.857 kHz ”. These switching frequencies and their harmonics are as shown in FIG.

  As shown in the figure, in this case, three harmonics overlap at “1000 kHz”. That is, the 12th harmonic of the switching frequency F01, the harmonic of the switching frequency F2011, and the 7th harmonic of the switching frequency F20 overlap each other. For this reason, the noise level increases at “1000 kHz”.

  Incidentally, it is not limited to the above condition that the frequency noise caused by the switching control is strengthened. For example, the frequency noise is also strengthened when the spreading frequency, which is the reciprocal of the repetition period T of the basic pattern, and its harmonics overlap the switching frequency and their harmonics in the AM broadcast band.

  For example, when the basic pattern has two shift amounts φ0 and φ1, and “φ0 = 1 μsec”, “φ1 = 2 μsec”, “T1 = 10 μsec”, and “T = 30 μsec”, “F01 = 90. 909 kHz ”and“ F10 = 83.333 kHz ”, and the spreading frequency is“ 50 kHz ”. For this reason, the 11th harmonic of the switching frequency F01, the 12th harmonic of the switching frequency F10, and the 20th harmonic of the spreading frequency are both “1000 kHz”.

  For this reason, it is better to set the basic pattern in a mode that eliminates the overlap between the spreading frequency and their harmonics and the switching frequency and their harmonics.

  According to the embodiment described in detail above, the following effects can be obtained.

  (1) The rising edge of the drive pulse is shifted by repeating a basic pattern composed of a plurality of shift amounts including different ones with respect to the basic period, and the spreading frequency that is the reciprocal of the repetition period of the basic pattern Was set above the audible frequency. For this reason, since it is possible to set such that the switching frequency created by the interval between the rising edges includes different ones, the switching frequency is spread compared to when they are equal, and as a result, noise caused by switching control is reduced. The average level can be reduced. Furthermore, by setting the spread frequency to be higher than the audible frequency, when the switching frequency overlaps with the predetermined frequency, it is possible to eliminate the reciprocal of the period from one overlap to the next overlap within the audible frequency band. It becomes possible. For this reason, since the noise finally output from the speaker 19 does not enter the audible frequency band, it is possible to suitably suppress disturbance of transmission of auditory information due to the noise.

  Furthermore, with this setting, the switching frequency is set to a long wave (LW) in which relatively low-order harmonics overlap with the AM broadcast band, a medium wave (MW) that is the AM broadcast band, or the like. Is possible. And the DC-DC converter 20 can also be reduced in size by setting a switching frequency to a comparatively high frequency in this way.

  (2) The shift amount is set so that harmonics of the respective switching frequencies created by the intervals between the rising edges do not overlap in a frequency band where noise countermeasures for the switching device are desired. For this reason, even if the frequency of a broadcast station selected in the AM broadcast band overlaps with a specific harmonic, this specific harmonic is one, so noise superimposed on the frequency of the broadcast station The level is reduced. Further, by setting such a setting, it is possible to avoid the frequency of the broadcasting station and all of the harmonics generated by the switching frequency from overlapping each other. Even if it overlaps with the frequency of, it can be surely made intermittent.

(Second Embodiment)
Hereinafter, the second embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  In the first embodiment, the switching frequency created by the interval between the rising edges of the drive pulse and their harmonics are diffused. However, even with these settings, the switching frequency created between the falling edges of the drive pulse and their harmonics, and further, the switching frequency created between the rising edges of the drive pulse and their harmonics overlap. The noise energy level increases at a specific frequency.

  That is, in the example shown in FIG. 6, when the pulse widths of the drive pulses are equal, the switching frequency F01 and the switching frequency f01 shown in FIG. 10 are equal, and the switching frequency F12 and the switching frequency f12 are In addition, the switching frequency F20 and the switching frequency f20 are equal.

  In the present embodiment, in order to avoid such a situation, as shown in FIG. 11, not only the shift amount φon0 to φon2 of the rising edge of the drive pulse but also the falling edge as compared with the basic period (start). By setting the shift amounts φoff0 to φoff2, the switching frequencies of both edges and their harmonics are set so as not to overlap in a frequency band where noise countermeasures are desired.

  On the other hand, there is a demand for controlling the output of the DC-DC converter 20 to a desired output. For this purpose, the operation mode of the power switching element 26 is required to be variable according to the required output. For this reason, in the present embodiment, the falling edge shift amounts φoff0 to φoff2 are variably set according to the required output, so that the drive pulse rises for each period (logic “H” level period). Alternatively, the duty (Duty), which is the ratio (or percentage) of the falling period (the period of the logic “L” level), is variably controlled. However, in this case, depending on the duty control mode, there is a possibility that the switching frequencies of the two edges and harmonics thereof overlap. For example, if the duty of each period in the basic pattern is set to be the same, there is a possibility that the switching frequencies of both the edges and their harmonics overlap at a predetermined duty.

  Therefore, in this embodiment, the average duty represented by the ratio of the total time of the logic “H” period (on period) of the drive pulse to the predetermined period or the total time of the logic “L” period (off period) of the drive pulse. The variable control of the duty is performed while making several duties different from each other during the basic period. For example, in FIG. 11, when the average duty in the repetition period T of the basic pattern is the required duty, the following relationship is satisfied, where the required duty is DT.

DT = {φoff0−φon0 + φoff1-φon1 + φoff2-φon2} / T
In order to perform duty control in such a manner, for example, a map illustrated in FIG. 12 may be provided in the memory 32 of the microcomputer 30. This map defines the relationship between the required duty and the shift amounts φoff0 to φoff2.

  The shift amount is set such that the switching frequencies created by the intervals between the rising edges and the falling edges of the drive pulse do not overlap with each other, and their harmonics are noise countermeasures for the switching device. It is set so as not to overlap each other in a desired frequency band.

  According to this embodiment described above, the following effects can be obtained in addition to the effects (1) and (2) of the first embodiment.

  (3) The start timing of the falling edge of the drive pulse with respect to the basic period is controlled to a desired control amount under the condition that the switching frequencies created by the intervals between the two edges do not overlap each other. Variable control was performed according to the required duty. Thereby, an increase in noise level due to overlapping switching frequencies can be avoided.

  (4) The variable control was performed while appropriately varying the duty of each period under the condition that the average duty within a predetermined period is the duty required when controlling the control target to a desired control amount. . Thus, the required duty can be set while preferably avoiding the switching frequencies from overlapping each other.

  (5) In a frequency band in which noise countermeasures for the switching device are desired, variable control of the duty is performed at a duty that does not overlap a plurality of harmonics of the switching frequency. Thereby, it is possible to avoid an increase in noise level at the frequency of the same harmonic due to the overlapping of the harmonics.

(Third embodiment)
Hereinafter, the third embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  In the present embodiment, information on a plurality of basic shift amounts including different ones and the order of the plurality of basic shift amounts, and an offset value are stored, and each basic shift amount, The basic pattern is generated by alternately arranging the basic shift amount plus the offset value.

  Specifically, as shown in FIG. 13, basic shift amounts Δ1 to ΔN, their order, and offset value Tos are stored in the memory 32 of the microcomputer 30. Therefore, the basic pattern is φ0 = Δ1, φ1 = Δ1 + Tos, φ2 = Δ2, φ3 = Δ2 + Tos,..., Φ (2N−2) = ΔN, φ (2N−1) = ΔN + Tos.

  According to this embodiment described above, the following effects can be obtained in addition to the effects (1) and (2) of the first embodiment.

  (6) A basic pattern is generated by storing information about a plurality of basic shift amounts Δ1 to ΔN and their order and the offset value Tos. Thus, in addition to information about the basic shift amounts Δ1 to ΔN and their order, only the offset value Tos is stored, and the number of shift amounts of the basic pattern is changed to the number of basic shift amounts Δ1 to ΔN. Can be doubled.

(Fourth embodiment)
Hereinafter, the fourth embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  In each of the above embodiments, the switching device can be downsized by setting the switching frequency to a relatively high frequency such as a long wave (LW) or a frequency band of AM broadcasting. However, as the switching frequency is increased, the slope of the rising edge and the falling edge of the drive pulse is set to be larger, so that the surge noise generated when the power switching element 26 is turned on and off is reduced. Easy to grow.

  Here, as shown in FIG. 14, the surge is peak noise generated in synchronization with the ON operation and the OFF operation, and ringing, which is noise that vibrates while being attenuated, follows this peak noise. The frequency of the oscillating noise (ringing frequency) has a resonance frequency determined by the structure of a circuit around the power switching element 26, such as a snubber circuit around the power switching element 26 and wiring inductance. Since this ringing frequency is usually “several MHz to several hundred MHz”, surge and ringing noise are superimposed on the frequency band of FM broadcasting.

  Therefore, in the present embodiment, the surge and ringing noise superimposed on the frequency band of FM broadcasting are diffused by the basic pattern. FIG. 15A shows an example in which surge noise synchronized with the rising edge of the drive pulse is diffused by a basic pattern composed of three different shift amounts (shift amounts φ0 to φ2). On the other hand, FIG. 15B shows surge and ringing that occur when drive pulses are periodically generated. In FIG. 15 (b), surge and ringing synchronized with the rising edge of the drive pulse occurs in period T1, whereas in FIG. 15 (a), the appearance period of surge and ringing is diffused by using the basic pattern. Yes.

  Here, a description will be given of how to set a basic pattern suitable for reducing the average energy level of surge and ringing in the FM band.

  In FIG. 16, the surge and ringing indicated by broken lines are shifted in phase by a quarter of the ringing period Tr with respect to the surge and ringing indicated by solid lines. In this case, the occurrence of surge and ringing peaks with a predetermined period can be preferably avoided. Thus, when the period Tr is shifted by “¼”, surge and ringing are preferably diffused. However, when there are three or more shift amounts, the difference between all the shift amounts cannot be “1/4” of the period Tr.

  Therefore, in the present embodiment, the difference (| φ0−φ1 |, | φ2−φ0 |) between the other shift amounts (φ1, φ2) with respect to any one shift amount (for example, φ0) is expressed as “Tr × {( 1/4 to 3/4) + N}: N = 0, 1, 2,. By setting in this way, among surges and ringing, it is preferable to avoid that surges having the highest energy level appear in the same cycle and that surge and ringing peaks strengthen each other. Can do. Furthermore, in this embodiment, the plurality of shift amounts are all set to be different from each other. This further diffuses surge and ringing. This can be realized by, for example, “φ0 = 0, φ1 = Tr / 4 + M × Tr, φ2 = 1/4 × Tr + N × Tr”.

  However, when switching control in such a manner is performed in a long wave band or a frequency band of AM broadcasting, it is desired to take measures against noise for AM broadcasting. At this time, if, for example, “φ0 = 0, φ1 = Tr / 4, φ2 = 5/4 × Tr”, etc., the rise of the drive pulse generated by the basic pattern shown in FIG. The switching frequency created by the interval between edges and their harmonics are substantially overlapped in the frequency band of AM broadcasting. Therefore, in order to take measures against noise in the frequency band of AM broadcasting, the shift amount is set so that the switching frequency includes those that do not overlap with each other in the frequency band of AM broadcasting. At this time, the shift amount difference is less than the basic period T1. Then, the spread frequency that is the reciprocal of the repetition period T of the basic pattern shown in FIG.

  According to the embodiment described above, the following effects can be obtained.

  (7) By setting the difference between other shift amounts with respect to any one shift amount to “Tr × {(1/4 to 3/4) + N}: N = 0, 1, 2,... Noise energy due to ringing can be diffused.

(Other embodiments)
The above embodiments may be implemented with the following modifications.

  In the fourth embodiment, the difference between other shift amounts with respect to any one shift amount is expressed as “Tr × {(1/4 to 3/4) + N}: N = 0, 1, 2,... did. However, in view of the fact that the noise has the largest energy level, a significant noise reduction effect can be obtained even if the difference in shift amount is set to “Tr × 1/4” or more. That is, it can avoid suitably that a surge appears for every basic period.

  In each of the above embodiments, the switching frequency, the spread frequency, and their harmonics are prevented from overlapping each other in a frequency band where noise countermeasures are desired, thereby reducing the noise energy level. In addition to this, the reciprocal of the basic period T1 shown in FIG. 6 and its harmonics may not overlap each other in a frequency band in which noise countermeasures are desired. This is particularly effective when using a reference clock whose oscillation frequency is the reciprocal of the basic period, as a method of shifting the start timing of the on operation and the off operation with respect to the basic period. This is because although the drive pulse for driving the power switching element 26 is different from the output of the reference clock, the reference clock and the power switching element 26 are connected by a wiring, and the reference clock is passed through this wiring. Is a noise source. In this case, however, the radiation noise of the reference clock can also be a noise source.

  In each of the above embodiments, the interval between the rising edges of the drive pulse is determined by the basic pattern, but the interval between the falling edges of the drive pulse may be determined. Alternatively, the logic “L” level of the drive pulse may be associated with the ON operation of the power switching element 26, and the logic “H” level of the drive pulse may be associated with the OFF operation of the power switching element 26.

  In each of the above embodiments, the desired frequency band of noise countermeasures for a device that performs switching control (switching device) is the entire frequency band of the target radio broadcast (for example, the entire AM frequency band “510 to 1710 kHz”). . With this setting, it is possible to take noise countermeasures by performing the same switching control even when the user receives any AM radio broadcast. However, the frequency band for which noise suppression is desired is not limited to the entire frequency band of the target radio broadcast. For example, the frequency band of “510 to 1000 kHz” of the AM frequency band and the frequency band of “1000 to 1710 kHz” including the broadcast station selected by the user is set as a frequency band for which noise countermeasures are desired. Also good. If the mode of switching control is changed depending on which of these two frequency bands the user has selected, the switching frequency and their harmonics do not overlap in each frequency band. Realization of setting becomes easy. That is, for example, when switching control is performed in an LW band lower than the AM frequency band, it is difficult to set so that harmonics do not overlap in the entire AM frequency band. For this reason, by variably setting the mode of switching control (basic pattern and duty control pattern), it is possible to easily perform setting so that harmonics do not overlap in the setting of each pattern. At this time, the spreading frequency may be set to be different for each basic pattern.

  The setting of the basic pattern and the duty control related to the switching control may be performed in such a manner that the carrier wave of each radio broadcasting station and the switching frequency and their harmonics do not overlap. In addition, in a vehicle equipped with a position detection device such as GPS, the frequency of a receivable broadcast station is detected based on the position of the vehicle detected by the position detection device, and the frequency and switching of the detected broadcast station are detected. The mode of switching control may be variably set so that the frequencies and their harmonics do not overlap. Even if such a setting is made, the switching frequency and harmonics thereof may overlap with the carrier wave of a receivable radio broadcast station due to a change in characteristics due to temperature or the like of the DC-DC converter 20 or the driver 40. It is effective to set the frequency to be higher than the audible frequency.

  The frequency signal for which noise countermeasures are desired for the switching device is not limited to a frequency signal transmitted by a radio broadcast station. For example, when an audio playback device such as an audio CD (Compact Disc) playback device or an MD (Mini Disc) playback device or a DVD (Digital Versatile Disc) playback device is mounted on a vehicle after product shipment, these playback targets There is one that outputs auditory information included in a medium as a frequency signal that can be received by the radio receiver 18. According to this apparatus, the auditory information of the medium to be reproduced is transmitted as a frequency signal in the radio frequency band, so that the auditory information is demodulated by the radio receiver 18 and then output from the speaker 19. Is possible. However, even in this case, audible noise may be output from the speaker 19 if the switching frequency or harmonics thereof overlap with the frequency used by the device. Therefore, the application of the present invention is also effective for such frequency signals. Incidentally, even in this case, the above setting for avoiding the inclusion of a plurality of switching frequencies and a plurality of harmonics within the bandwidth per radio station that approximates the frequency used by the device is effective. is there. For this reason, even if noise countermeasures are desired only for the frequency signal transmitted by the device, each of the above in the entire frequency band of the radio used by the device (for example, the entire frequency band of the AM broadcast). Noise countermeasures may be taken as in the embodiment.

  When the switching frequency and their harmonics intermittently overlap with the desired frequency for noise suppression for the switching device, the reciprocal of the period from one overlap to the next overlap is within the audible frequency band. The setting that does not fall within the range is not limited to the setting that sets the spread frequency to an audible frequency or higher. For example, by appropriately setting the shift amount of the basic pattern or the like, even when the switching frequency schematically illustrated in FIG. 17 is used, the switching frequency and the reciprocal of the period in which those harmonics overlap with the predetermined frequency, It can be prevented from entering the audible frequency band. FIG. 17 illustrates a case where noise countermeasures are implemented in a long wave (LW) band broadcast band (“30 to 300 kHz”). In FIG. 17, the switching frequency created by the basic pattern is composed of four “50 kHz”, “47 kHz”, “60 kHz”, and “53 kHz”. For this reason, the spread frequency is about “13 kHz” and falls within the audible frequency band. However, here, if the predetermined frequency is “300 kHz”, there are two switching frequencies, “50 kHz” and “60 kHz”, and these harmonics overlap with the predetermined frequency. The reciprocal of the period is about “24 kHz” and exceeds the audible frequency. However, in this example, when a frequency other than “300 kHz” is received, noise due to the switching frequency and harmonics thereof is output as an audible range.

  In FIG. 17, the sixth harmonic of the switching frequency of “50 kHz” and the fifth harmonic of the switching frequency of “60 kHz” overlap, and this is an approximation of the order of the harmonics when overlapping. It is an example. On the other hand, for example, when the 5th harmonic and the 20th harmonic overlap, the order of the harmonics at the time of overlapping is greatly separated, and the period between the timings at which they overlap with the predetermined frequency is increased. There may be a case where the reciprocal is equal to or higher than the audible frequency. However, in this case, since the energy level of the 20th harmonic superimposed on the predetermined frequency is extremely small, it is substantially from the speaker depending on the period between the timings at which the predetermined frequency and the fifth harmonic overlap. Whether or not audible noise is output is determined. For this reason, in this case, the spreading frequency is set higher than the audible frequency.

  Incidentally, in FIG. 17, when the order of the switching frequencies determined by the basic pattern is “50 kHz”, “60 kHz”, “47 kHz”, “53 kHz”, the period in which these harmonics overlap with the predetermined frequency. The reciprocal of is approximately “13 kHz”, which is an audible frequency.

  ・ Furthermore, when the spreading frequency is set to be lower than the audible frequency (for example, “20 Hz” or lower), the switching frequency and their harmonics are intermittently overlapped with a predetermined frequency desired for noise countermeasures for the switching device. In addition, the reciprocal of the period from one overlap to the next may not be within the audible frequency band. However, at this time, as shown in FIG. 17, when the switching frequency and a plurality of harmonics thereof overlap with the predetermined frequency, the reciprocal of the period between the overlapping timings can fall within the audible frequency band. There is sex. For this reason, when the switching frequency and the number of harmonics thereof overlap the predetermined frequency, the spreading frequency is set to “audible frequency (for example,“ 20 Hz ”) / (multiple number)” or less. It is desirable.

  The method of setting the average duty as the required duty is not limited to that exemplified in the first embodiment. For example, as shown in FIG. 18, an average duty that is a ratio of a rising period or a falling period of the drive pulse to a predetermined period Tc longer than the repetition period of the basic pattern may be set as the required duty. At this time, if the switching frequencies determined by the basic pattern do not overlap with each other, the spreading frequency, which is the reciprocal of the repetition period T of the basic pattern, is set to an audible frequency or higher, thereby achieving the effect (1) of the first embodiment. Can be obtained.

  In the third embodiment, the basic pattern may be generated using the basic shift amounts Δ1 to ΔN and the offset value Tos as in the second embodiment. At this time, as shown in FIG. 19, if an offset value is used for every two basic patterns, even if the basic shift amounts Δ1 to ΔN are set to very small values, they are generated by the basic pattern. The frequency difference between the switching frequencies can be equal to or greater than the AM broadcast bandwidth.

  That is, by setting the offset value to a large value, for example, the adjacent switching frequency F01 = 1 / (T1−φ0 + φ1) = 1 / (T1−Δ1 + Δ2) and F12 = 1 / (T1−φ1 + φ2) = 1 / (T1 + Tos) ) Can be made equal to or greater than the bandwidth.

  -Control performed in order to make control object into the desired control amount is not restricted to Duty control of the said aspect. In short, even if the switching frequency set when performing the above-mentioned control and the harmonics thereof overlap with a predetermined frequency desired for noise countermeasures for the switching device, it is only necessary to make it overlap only intermittently. . Then, by preventing the period from the overlap to the next overlap from entering the audible frequency band, the noise output from the speaker due to the overlap can be driven out of the audible range.

  When the switching frequency and their harmonics intermittently overlap with the desired frequency for noise suppression for the switching device, the reciprocal of the period from one overlap to the next overlap is within the audible frequency band. The switching device that is set so as not to enter is not limited to a device that repeats an on operation and an off operation based on the basic pattern. For example, a predetermined number of shift amounts are associated with a predetermined number, and the amount of shift for turning on or off the power switching element 26 by the number that matches the number generated by the random number generator. May be selected. Even in this case, (a) when a specific shift amount is newly selected by the random number generator, the switching frequency determined by this and its harmonics, and noise countermeasures for the switching device are desired. A process for determining whether or not a predetermined frequency overlaps; (b) a process for calculating the reciprocal of a period from one overlap to the next when it is determined to overlap; (c) the calculated reciprocal is When entering the audible frequency band, if the process of generating the number again by the random number generator is performed without operating the power switching element 26 at the selected switching frequency, the first first step is performed. The effect according to the effect (1) of the embodiment can be obtained.

  The switching control by the switching device that performs the switching control that repeats the ON operation and the OFF operation of the power switching element is not limited to the DC-DC converter 20 illustrated in FIG. For example, an insulation type DC-DC converter 50 of the type shown in FIG. 20 may be used. In the DC-DC converter 50, a series connection body of power switching elements 52 and 53 and a series connection body of power switching elements 54 and 55 are connected in parallel to the high voltage battery 51. A capacitor 56 and a coil 58 a of a transformer 58 are connected between the power switching element 52 and the power switching element 53 and between the power switching element 54 and the power switching element 55. On the other hand, a diode 59 and a diode 60 are connected to both ends of the coil 58b of the transformer 58, respectively. The cathodes of the diode 59 and the diode 60 are both connected to the coil 61. The other terminal of the coil 61 is connected to the capacitor 62. The node N of the coil 58b of the transformer 58 and the other terminal of the capacitor 62 are grounded. Incidentally, the voltage between both terminals of the capacitor 62 is the output of the DC-DC converter 50.

  Further, the inverter 70 is not limited to the DC-DC converter, and may be, for example, the inverter 70 illustrated in FIG. In this figure, an example in which the inverter 70 is connected to the power steering motor 80 is shown. In this inverter 70, a direct connection body of power switching elements 71 and 72, a serial connection body of power switching elements 73 and 74, and a serial connection body of power switching elements 75 and 76 are connected in parallel between a power supply voltage and ground. It has been done. And the output of an inverter is taken out between two power switching elements (for example, between the power switching element 71 and the power switching element 72) among each said serial connection body. Incidentally, the voltage of the node a changes as shown in FIG. 21B by switching control.

  The switching frequency set by the basic pattern is not limited to the AM broadcast frequency band or long wave, but may be, for example, an FM broadcast frequency band.

  In addition, the switching device is not limited to a device mounted on a vehicle such as a hybrid vehicle. However, when the switching device is mounted on a vehicle, the application of the present invention is particularly effective because noise may be mixed into the car audio or the like due to switching control.

The figure which shows the structure of the vehicle of the hybrid vehicle by which switching apparatus is mounted about 1st Embodiment. The circuit diagram which shows the structure of the DC-DC converter in the same embodiment. The figure for demonstrating the problem concerning switching control. The figure which shows the experimental result of the noise which arose by switching control. The figure which shows the experimental result of the noise which arose by another switching control. The figure which shows the aspect of the switching control concerning the embodiment. The figure which shows the example in which the harmonic of a switching frequency overlaps. The figure which shows an example of the switching frequency and its harmonic in the embodiment. The figure which shows another example of the switching frequency in the same embodiment, and its harmonic. The figure explaining the problem of Duty control. The figure which shows the Duty control aspect concerning 2nd Embodiment. The figure which shows the map data for performing Duty control in the embodiment. The figure which shows the basic pattern of 3rd Embodiment. The wave form diagram which shows surge noise. The figure which shows the spreading | diffusion aspect of the surge noise in 4th Embodiment. The figure which shows the spreading | diffusion aspect of the surge noise in 4th Embodiment. The figure which shows the modification of each said embodiment. The figure which shows the modification of the said 2nd Embodiment. The figure which shows the modification of the said 3rd and 4th embodiment. The circuit diagram which illustrates another composition of a DC-DC converter. The circuit diagram of the inverter used as the application object of a switching apparatus.

Explanation of symbols

  20 ... DC-DC converter, 26 ... power switching element, 30 ... microcomputer.

Claims (12)

In a switching device that performs switching control that repeats ON and OFF operations of a power switching element,
Phase shift means for shifting the start timing of any one of the on operation and the off operation by repeating a basic pattern composed of a plurality of shift amounts including different ones with respect to a basic cycle,
A switching device characterized in that a spreading frequency which is the reciprocal of the repetition cycle of the basic pattern is set to an audible frequency or higher . 2. The switching device according to claim 1, wherein the basic patterns are set such that shift amounts of any one of the start timings are different from one another . The phase shift means includes means for storing a plurality of basic shift amounts including different ones, information on the order of the plurality of basic shift amounts, and an offset value, and each of the basic shift amounts. 3. The switching device according to claim 1, wherein the basic pattern is generated by appropriately arranging a shift amount that becomes and a value obtained by adding the offset value to each basic shift amount . The phase shift means sets the shift amount so that harmonics of each switching frequency created by each of the intervals between the start timings do not overlap each other in a frequency band of a radio broadcast where noise countermeasures are desired. The switching device according to claim 2 . The phase shift means includes a start timing with respect to the basic cycle for either one of the on operation and the off operation, an interval between the start timings of the on operation and an interval between the start timings of the off operation. 5. The apparatus according to claim 1, further comprising: a duty control unit that variably controls the control target according to a duty required when the control target is controlled to a desired control amount under a condition that the switching frequencies generated by the control unit do not overlap each other. The switching device described . The duty control means sets an average duty represented by a ratio of a total time of an on period or a total time of an off period to a predetermined period as a duty required when controlling the control target to a desired control amount. The switching device according to claim 5, wherein the variable control is performed under conditions . The duty control means is configured to overlap a plurality of harmonics of the switching frequency formed by an interval between the start timings of the on operation and an interval between the start timings of the off operation in a frequency band of a radio broadcast where noise countermeasures are desired. The switching device according to claim 5 or 6, wherein the duty variable control is performed at a duty that does not occur . The switching device according to claim 4 or 7, wherein the harmonics overlap means that a frequency difference thereof is within a bandwidth per broadcasting station of the wireless broadcast . In a switching device that performs switching control that repeats ON and OFF operations of a power switching element,
The start timing of one of the on operation and the off operation is performed while being shifted by a plurality of shift amounts including different ones with respect to a basic cycle, and the interval between the start timings of either one is Even if at least one of the switching frequency and their harmonics is intermittently overlapped with a predetermined frequency in the frequency band of radio broadcasting, the reciprocal of the time between the overlaps is the audible frequency band. A switching device that is set so as not to enter . In a switching device that performs switching control that repeats ON and OFF operations of a power switching element,
The start timing of one of the on operation and the off operation is performed while being shifted by a plurality of shift amounts including different ones with respect to a basic cycle, and the interval between the start timings of either one is If at least one of the switching frequency and their harmonics is predicted to intermittently overlap with a given frequency within the radio frequency band, the reciprocal of the time from one overlap to the next is audible A switching device , wherein the shift amount is changed so as not to fall within a frequency band . The switching device according to claim 9 or 10, wherein the overlapping with the predetermined frequency means that a frequency difference with the predetermined frequency is within a bandwidth per broadcasting station of the wireless broadcast . When Tr is a period of ringing caused by a surge caused by at least one of the on operation and the off operation, the difference between other shift amounts with respect to an arbitrary shift amount among the plurality of shift amounts is “Tr × 1 / The switching device according to claim 1, wherein the switching device is set to 4 ”or more.

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